Today, it is a common approach within the food processing industry as well as other industries to use tubular heat exchangers for heat treatment purposes.
Within the food processing industry it is common to have the tubular heat exchanger manufactured in stainless steel. A steel grade of insert tubes and shell tubes, placed outside the insert tubes, can be chosen depending on the product to be processed.
In short, by example, product enters the tubular heat exchanger in the insert tubes at low temperature and is heated by a media flowing in the shell tubes outside the insert tubes. When the product reaches pasteurization temperature it enters a cell either included in the heat exchanger or separate, a tube with a length adjusted to keep the product at pasteurization temperature for a certain time calculated for each product case. After the holding cell, the product starts cooling down; media now flows outside the insert tubes in the shell tubes. Preferably, insert tubes, shell tubes and holding cells are arranged so they can treat different products and cases.
In order to reduce heat transfer, insert tubes and shell tubes used for heating the product can be grouped together, and in the same way insert tubes and shell tubes used for cooling the product can be grouped together. By doing so the heat transfer between different parts within the tubular heat exchanger can be reduced, and hence the energy efficiency can be increased.
Another approach to reduce the energy transfer within the tubular heat exchanger is to insulate the shell tubes by using for example mineral wool or cellular rubber. Since a vast amount of energy is used for heat treatment in e.g. a food processing plant there is a need to reduce this in order to be able to provide heat treatment in a more environmental friendly way.